Many cellular telephones with, for example, a Global System for Mobile communications (GSM) modulation utilize two frequency bands: 824 MHz to 915 MHz and 1710 MHz to 1910 MHz. To utilize both frequency bands, cellular telephones include multiple power amplifier (PA) line-ups in typical radio frequency front-end modules. In GSM cellular telephones, there are typically two PA line-ups: one line-up for low frequency band signals (e.g., 824 megahertz (MHz) to 915 MHz), and one line-up for high frequency band signals (e.g., 1710 MHz to 1910 MHz).
Separate line-ups for low frequency band signals and high frequency band signals is desirable because of the significant difference in the impedance matching networks and harmonic filter systems needed for each signal band. In other words, the PA output impedance matching network for low frequency band signals does not work well in matching a high frequency band PA to antenna switch impedances. If a typical single PA line-up is utilized for both frequency bands, an optimized low frequency signal band matching network will create significant mismatch for high frequency signal band operations and consequently, too high of an insertion loss. Moreover, the harmonic filter circuit for low frequency band signals is not desirable for high frequency band signals because a low frequency band harmonic filter would almost completely reject the high frequency band transmitting signal. Accordingly, current cellular telephones have a system utilizing two or more PA line-ups, which increases the cost and size of the cellular telephone.
Accordingly, it is desirable to provide methods and apparatus to enable the combination of two or more frequency bands into a single PA line-up. In addition, it is desirable to utilize such apparatus and methods to reduce the overall product size and cost of a communication device. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.